Bug 1456680 - Part 6: Refactor getting the grid highlighter settings logic into HighlightersOverlay. r=pbro
- Refactor the logic for getting the grid highlighter settings into HighlightersOverlay.js
- Refactor the grid area and cell highlight into a single function in grid-inspector.js
- Change the order of the parameters for onHighlighterChange in grid-inspector.js
- Get the last highlighted state from the Redux store instead of storing them in a variable